The yarn measuring and supplying device for a known type of air jet loom includes a rotatable yarn winding drum to which yarn is fed tangentially through a radial slot in a cylindrical drum cover from a suitable supply, e.g., a package, and from which yarn is withdrawn laterally or endwise from one end of the drum. Telescoped into that end of the drum is a short cylinder having along the corresponding end edge a circular array of yarn-catching fingers extending parallel to the cylinder axis. The cylinder is of slightly smaller diameter than the drum and is rotatable therewith but also is reciprocable on its axis to extend the fingers out of the drum into catching engagement with the withdrawn yarn end to wind yarn onto the drum, or retract the fingers at least partly into the drum to release the wound yarn for withdrawal from the corresponding end of the drum. Secured to the cylindrical drum cover over the fingers is a yarn guide end cover plate, somewhat concave on its inner side and having a central circular opening aligned with the axis of the drum. The inner side of the cover plate is formed with an annular groove or channel into which the circular array of fingers loosely fits when extended.
In operation of such a measuring and supplying device, the fingers are extended to catch the yarn, the drum and fingers rotated to wind a predetermined length of yarn onto the drum, rotation of the drum and fingers stopped, the fingers retracted to release the yarn withdrawal end, and the measured length withdrawn through the central opening in the end cover plate by the inserting device. The cycle is then repeated.
While such yarn measuring and supplying device is in use on looms presently in commercial operation, it possesses disadvantages. In particular, it has a strong tendency to break or otherwise damage yarn filaments, especially glass or fiberglass filaments, by the abrupt bends imposed therein in being pushed into the annular channel in the end cover plate. Moreover, unless the yarn-catching cylinder is carefully fitted and adjusted, with relation to the end cover plate, and vice-versa, the yarn-catching fingers engage and rub against the end cover plate with resulting damage to one or both. Moreover, considerable jump rope motion, or the phenomenon known as "ballooning", of the yarn occurs in its travel from the central hole in the end cover plate to the inserting device, which may be an air jet nozzle. Such ballooning not only tends to damage the yarn PG,4 but also to wear excessively the yarn entrance of the inserting device. Further, the end cover plate is relatively expensive.
U.S. patents relating to somewhat comparable yarn measuring and supplying devices are:
Bucher, U.S. Pat. No. 3,276,484, Oct. 4, 1966 PA1 Bucher, U.S. Pat. No. 3,411,547, Nov. 19, 1968 PA1 Hosono et al, U.S. Pat. No. 3,674,057, July 4, 1972 PA1 Tannert, U.S. Pat. No. 3,709,444, Jan. 9, 1973 PA1 Rosen, U.S. Pat. No. 3,904,141, Sept. 9, 1975
The devices disclosed in these patents, however, possess one or more of the disadvantages described above, and especially tend to cut or break glass yarn filaments.